1. Technical Field
The present invention relates to a roll medium supporting apparatus including a base body portion to be inserted into a hollow shaft portion of a rolled medium, and a plurality of contact supporting portions being provided circumferentially of the base body portion so as to be displaceable radially of the hollow shaft portion, having a plurality of predetermined positions within the displaceable range, and coming into contact with the inner peripheral surface of the hollow shaft portion and supporting the same, and a printing apparatus having the roll medium supporting apparatus.
In this application, the printing apparatus includes various types such as ink jet printers, wire dot printers, laser printers, line printers, copying machines, and facsimile machines.
2. Description of the Related Art
In the related art, a roll paper holder as a roll medium supporting apparatus provided in a printing apparatus includes a boss member as a base body portion and an impeller member as a contact supporting portion as shown in JP-A-2007-290864 and JP-A-2007-290865. The impeller member is provided so as to be capable of coming into contact with the inner peripheral surface of a hollow shaft of a roll paper shaft. The impeller member is provided so as to be displaceable radially of a roll paper shaft portion with respect to the boss member by rotating a cam lever member.
Therefore, when setting roll paper shafts having different diameters, they are accommodated only by rotating the cam lever member. In other words, it is adapted to change the diameter of the roll paper holder by displacing the impeller member without using an adapter for changing the diameter of the roll paper holder.
For example, setting a roll paper shaft having a diameter of 2 inches is enabled by rotating the cam lever member in one direction after having displaced, that is, after having closed the impeller member radially inwardly.
On the other hand, setting a roll paper shaft having a diameter of 3 inches is enabled by rotating the cam lever member in the opposite direction after having displaced, that is, after having opened the impeller member radially outwardly.
However, when the cam lever member is ill-positioned, the impeller member is also ill-positioned. When the roll paper shaft of 3 inches is set in a state in which the impeller member is half-way opened, it may cause slippage between the roll paper holder and the roll paper shaft of 3 inches, whereby paper may be sagged. In such a case, a sag of the paper might not be controlled.
When an attempt is made to set the roll paper shaft of 2 inches in a state in which the impeller member is half-way closed, the impeller member might be caught on the roll paper shaft, whereby setting might not be achieved.